So far, the compound of formula (II): ##STR2## [hereinafter sometimes referred to as "cromoglycic acid (II)"], which has antiallergic activity, has been used as an antiallergic agent generally in its sodium salt form.
Since it cannot be absorbed in the digestive tract, cromoglycic acid (II) has been administered generally by spraying for inhalation into the nostrils or oral cavity using a sprayer for exclusive use for that purpose.
However, this method of administration is disadvantageous in that difficulties in connection with the operation of the sprayer are encountered in the process of inhalation (especially in young children and the aged).
Therefore, development of cromoglycic acid derivatives absorbable even after oral administration has been earnestly desired.
Accordingly, it is a primary object of the invention to provide cromoglycic acid derivatives which are orally administrable and have high antiallergic activity.
A second object of the invention is to provide a method of producing the noted derivatives.
A third object of the invention is to provide pharmaceutical compositions, for example antiallergic compositions for oral application, which contain said compounds.